text: Approximately 7.1 million dry tons of biosolids were generated in 2004 at approximately 16,500 municipal wastewater treatment facilities in the United States.
  In the United States, as of 2013 about 55% of sewage solids are used as fertilizer. Challenges faced when increasing the use of biosolids include the capital needed to build anaerobic digesters and the complexity of complying with health regulations. There are also new concerns about micro-pollutions in sewage (e.g. environmental persistent pharmaceutical pollutants), which make the process of producing high quality biosolids complex. Some municipalities, states or countries have banned the use of biosolids on farmland.